<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			div{
				height: 400px;
				width: 200px;
				border: 2px solid red;
			}
			.d1{
				border 5px groove blue;
				text-align: center;
				border-radius: 50%;
				width: 400px;
			}
		</style>
		<script src="../js/jquery-3.4.1.min.js"></script>
		<script>
			$(function(){
				let d=$("div");
				//alert("高度:"+d.css("height"));
				//alert("宽度:"+d.css("width"));
				//alert("边框颜色:"+d.css("border-color"));
				alert(d.html());
				d.html("<h1>在不天晴,就要没衣服穿了</h1>");
				$("#b1").click(function(){
					$("div").addClass("d1");
				});
				$("#b2").click(function(){
					$("div").toggleClass("d1");
				});
				$("#b3").click(function(){
					let f=$("div").hasClass("d1");
					alert(f);
				});
				$("#b4").click(function(){
					$("div").removeClass("d1");
					
				});
			});
		</script>
	</head>
	<body>
		<div>
			马上就要天晴了
		</div>
		<p>
			<button type="button" id="b1">增加样式</button>
			<button type="button" id="b2">toggle样式</button>
			<button type="button" id="b3">判断是否有样式</button>
			<button type="button" id="b4">删除样式</button>
		</p>
	</body>
</html>
